[google-genai] CHANGELOG: replace PR-number placeholder with open-telemetry#24

Assisted-by: opencode agent

Author: Achuth17

instrumentation/opentelemetry-instrumentation-google-genai/CHANGELOG.md

@@ -14,7 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   identifiers) that should not land on broadly-sampled spans. On key
   collisions with `GENERATE_CONTENT_EXTRA_ATTRIBUTES_CONTEXT_KEY`, the
   event-only value wins on the event.
-  ([#XXXX](https://github.com/open-telemetry/opentelemetry-python-genai/pull/XXXX))
+  ([#24](https://github.com/open-telemetry/opentelemetry-python-genai/pull/24))
 -Add `gen_ai.usage.reasoning.output_tokens` attribute to capture thinking tokens on spans/events when the experimental sem conv flag is set. Add thinking tokens to output tokens. ([#4313](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4313))
 -Add `gen_ai.usage.cache_read.input_tokens` attribute to capture cached tokens on spans/events when the experimental sem conv flag is set. ([#4313](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4313))